for the cost of doing it right; and to whatever degree you backed off doing it right you'd end up missing the point.
The big win of text based matching is that nobody has to prepare to be indexed in a search engine, search engine optimization notwithstanding. The big loss is that you get false matches due to polysemy (words that have more than one meaning) and false misses due to synonymous words whose equivalence the search engine doesn't know about.
If you go to something like RDF in which concepts have unique identifiers (URIs), the marginal win is that you get precise and accurate matches where a concept used in two places. I can write an app which searches the Internet for articles on John Williams the classical guitarist and not accidentally lead him to articles on John Williams the movie composer. The big downside is that content providers have to think carefully about how to index your content.
So the problem with the semantic web is that what is realistically achievable with semantic technologies is only a marginal (though real) improvement over what we have now, but that improvement requires content providers to make some effort. I have no expectation that everybody will do this, so the semantic web isn't likely to revolutionize everyone's web experience anytime soon. But I think it can serve many useful niche purposes.